How can I correctly set up a subdomain redirect for my online store?

[Mattematiss1]

Hi!

I've been in touch with Shopify support regarding a subdomain we're working on setting up. We already have the store www.tides.no working (not launched yet) where we intend to sell to our local customers in NOK and want to set up a second store on usd.tides.no for selling in $. As Shopify Pay / Markets isn't available in Norway yet, this seems to be the best workaround for now.
We're having issues setting up the subdomain and getting error messages or a very strangely looking store not at all like in the editor when visiting usd.tides.no. Shopify support directed me to a community post with his code which they say will fix the issue, but it needs to be edited for our domain:

<script>
if (window.location.href == "https://dexshellstore.com/collections/waterproof-hats/products/beanie-fair-isle") {
   window.location.href = 'https://dexshellstore.com/products/beanie-fair-isle'; 
}
</script>

I'm not proficient with coding and I have no idea what address to redirect from and to, to get things working.

I hope someone can help:)

Thanks!